Matthew C. Perry

Blood chemistry and hematocrit of captive and wild canvasbacks

Blood chemistry and packed cell volume (PCV) did not vary among groups of captive canvasbacks (Aythya valisineria) maintained ad libitum on 5 diets varying in metabolizable energy (ME) and protein. Ducks fed low quality diets increased their consumption so that all ducks were obtaining similar amounts of energy and protein. Some variables, including cholesterol, were found to differ between the sexes and ages of captive ducks. Seasonal differences were detected in the blood chemistry of captive canvasbacks. Four of the 5 enzyme values increased from October to January and then declined to April. PCV increased from 45 in October to 51 in April. Overall, blood chemistry values and PCVs were highly variable and did not appear to be good discriminators for age, sex, and diet of captive canvasbacks. Differences detected between captive and wild canvasbacks were attributed to increased stress of wild ducks during handling. J. WILDL. MANAGE. 50(3):435-441 Most studies dealing with avian blood have been conducted with chickens and other domestic birds (Lucas and Jamroz 1961, Sturkie 1976), and their emphasis has been on hematology rather than blood chemistry. Other studies have been conducted on the blood of birds other than Anseriformes (Ronald et al. 1968, Carey and Morton 1976, Rehder et al. 1982, Parrish and Mote 1984). Gee et al. (1981) compared differences in 25 blood chemistry values among 12 captive avian species; 7 of these were endangered species and included quail (Odontophorinae), raptors (Falconiformes), cranes (Gruidae), and geese (Anserini). Several researchers have demonstrated that the physiological condition of birds can influence blood values (Altman and Dittmer 1964, Dolnik 1973, Driver 1981). Gee et al. (1981) showed differences in blood values due to sex; however, Mulley (1979, 1980) was unable to demonstrate differences in blood chemistry and hematology due to sex with 2 duck species in Australia. Other researchers have shown the effect of age (Leonard 1969, Sturkie 1976). Woerpel and Rosskopf (1984) reviewed the use of blood chemistry as an aid in the diagnosis of disease and illness in caged birds. Several research studies have been conducted concerning factors affecting certain blood values of waterfowl. Wood and Hofman (1967) found that blood values of mallards (Anas platyrhynchos) could be influenced by artificial stimulation of reproduction, and Wood and Smoes (1968) reported the effects of reproducti e suppression on the blood of mallards. Mori and George (1978) studied seasonal effects on certain blood serum variables of Canada geese (Branta canadensis). Kocan (1972) conducted hematological analyses on 54 canvasbacks from Chesapeake Bay. Although PCV for male and female canvasbacks overlapped, there was a tendency for higher values in females (. = 53) than in males (9 = 51). In another sample of canvasbacks Kocan and Pitts (1976) reported higher PCV values in females than males although ages were not determined. They stated that differences observed among adult ducks probably reflected hormonal and nutritional differences brought about by changing photoperiod and migration. Hemm and Carlton (1967) reported conflicting PCV data in ducks due to age and sampling variability. More recent reports on waterfowl PCV values show little differences between sexes (Williams and Trainer 1971, Shave and Howard 1976, Mulley 1979). There are indications that differences in PCV exist between dabbling and diving ducks (Bond and Gilbert 1958, Shave and Howard 1976). The influence of nutrients on the blood chemistry of waterfowl has not been determined adequately. Newberne (1975) discussed the importance of diet in research experiments with regard to changing physiological processes, but he did not give specific examples of changes that occurred in blood due to diet. Most blood analyses conducted with waterfowl have been done with breeding ducks with emphasis

Review of factors affecting the distribution and abundance of waterfowl in shallow-water habitats of Chesapeake Bay

Long-term trends of waterfowl populations in Chesapeake Bay demonstrate the importance of shallow-water habitats for waterfowl species. Although recent increases in field feeding by geese and swans lessened the importance of shallow-water areas for these species, most duck species depend almost exclusively on shallow-water habitats. Many factors influenced the distribution and abundance of waterfowl in shallow-water habitats. Habitat degradation resulted in the decline in numbers of most duck species and a change in distribution of some species. Increased numbers of mallards (Anas platyrhynchos) in recent decades probably resulted from release programs conducted by the Maryland Department of Natural Resources and private individuals. Studies of food habits since 1885 showed a decline in submerged-aquatic vegetation in the diet of some species, such as the canvasback (Aythya valisineria), and an increase in the proportions of invertebrates in the diet. Diversity of food organisms for many waterfowl species has declined. Surveys of vegetation and invertebrates in the Chesapeake Bay generally reflect a degradation of shallow-water habitat. Human population increases in the Chesapeake Bay watershed directly and indirectly affected waterfowl distribution and abundance. The increase of exotic plant and invertebrate species in the bay, in most cases, benefited waterfowl populations. Increased contaminants have reduced the quality and quantity of habitat, although serious attempts to reverse this trend are underway. The use of shallow-water habitats by humans for fishing, hunting, boating, and other recreational and commercial uses reduced the use of shallow-water habitats by waterfowl. Humans can lessen the adverse influences on the valuable shallow-water habitats by restricting human population growth near these habitats and improving the water quality of the bay tributaries. Other affirmative actions that will improve these areas for waterfowl include greater restrictions on boat traffic in shallow-water habitats and establishing more sanctuaries in shallow-water areas that have complete protection from human disturbance. *** DIRECT SUPPORT *** A01BY074 00013

Effects of Dietary Selenium on Tissue Concentrations, Pathology, Oxidative Stress, and Immune Function in Common Eiders (Somateria mollissima)

Common eiders (Somateria mollissima) were fed added Se (as L-selenomethionine) in concentrations increasing from 10 to 80 ppm in a pilot study (Study 1) or 20 (low exposure) and up to 60 (high exposure) ppm Se in Study 2. Body weights of Study 1 ducks and high-exposure ducks in Study 2 declined rapidly. Mean concentrations of Se in blood reached 32.4 ppm wet weight in Study 1 and 17.5 ppm wet weight in high-exposure birds in Study 2. Mean Se concentrations in liver ranged from 351 (low exposure, Study 2) to 1252 ppm dry weight (Study 1). Oxidative stress was evidenced by Se-associated effects on glutathione metabolism. As Se concentrations in liver increased, Se-dependent glutathione peroxidase activity, glutathione reductase activity, oxidized glutathione levels, and the ratio of hepatic oxidized to reduced glutathione increased. In Study 2, the T-cell-mediated immune response was adversely affected in high-exposure eiders, but ducks in the low-exposure group exhibited evidence of an enhanced antibody-mediated immune response. Gross lesions in high-exposure ducks included emaciation, absence of thymus, and loss of nails from digits. Histologic lesions included severe depletion of lymphoid organs, hepatopathy, and necrosis of feather pulp and feather epithelium. Field studies showed that apparently healthy sea ducks generally have higher levels of Se in liver than healthy fresh-water birds, but lower than concentrations found in our study. Data indicate that common eiders and probably other sea ducks possess a higher threshold, or adverse effect level, for Se in tissues than fresh-water species. However, common eiders developed signs of Se toxicity similar to those seen in fresh-water birds.

Influence of nutrients on feed intake and condition of captive canvasbacks in winter

Dramatic changes in the food habits and distribution of canvasbacks (Aythya valisineria) in Chesapeake Bay during the 1970s generated a need to evaluate the nutritional value of food items and the requirements of this species on its wintering grounds. Groups of captive canvasbacks were maintained ad libitum on 5 diets during the winters of 1978-79 and 1979-80 to evaluate the effects of varying protein and energy levels on feed intake and condition. Feed intake during the 1979-80 winter was 42% greater for those ducks fed the low energy (1,543 kcal/kg) diet than for those fed the high energy (3,638 kcal/kg) diet. Canvasbacks fed the high energy diet, however, consumed 317 kcal/bird day, whereas those fed the low energy diet consumed only 191 kcal/bird day. Body weight of males and females did not differ among groups fed different diets, but there were seasonal differences (P < 0.05) for both sexes aggregated across diets. Data from this study indicate that canvasbacks may be unable to adjust intake rates to compensate for low energy foods and subsequently may store less fat or modify behavior. However, decreased weight, feed intake, and activity of ducks fed ad libitum rations occurred in mid-winter irrespective of diet quality and appeared to be an endogenous component of their annual cycle that persists in captivity. These changes apparently have a selective advantage of increasing the probability of survival in ducks by decreasing energy expenditure during periods of winter stress. J. WILDL. MANAGE. 50(3):427-434 Aerial winter waterfowl surveys conducted by the U.S. Fish and Wildlife Service from 1955 to 1979 indicated that the winter population of canvasbacks in North America has ranged from 481,000 in 1955 to 179,000 in 1972 (Perry et al. 1981). The winter population in Chesapeake Bay (Md. and Va.) averaged 31% of the North American population and 62% of the Atlantic Flyway population. During 1955-79, numbers of canvasbacks declined substantially in Chesapeake Bay, the Atlantic Flyway, and North America (Perry et al. 1981). During the 1970s in the Atlantic Flyway, the percent of canvasbacks wintering in Chesapeake Bay decreased, whereas percentage increases occurred in New Jersey and North Carolina. Increases in New Jersey remain unexplained (Perry 1982), but increases in North Carolina may be related to better habitat conditions due to a larger number of freshwater impoundments (Perry and Uhler 1982). These wetlands provide abundant aquatic vegetation, which has traditionally been an important winter food for canvasbacks. Vegetation surveys from 1971 to 1979 showed Present address: 7 Crestwood Drive, Tolland, CT 06084. a decline in the frequency of occurrence and biomass of submerged aquatic plants in Chesapeake Bay (Kerwin et al. 1976, Bayley et al. 1978, Orth and Moore 1981, Haramis and Carter 1983). Turbidity and herbicides have been implicated in the decline of vegetation (Stevenson and Confer 1978). Two exotic aquatic plants, waterchestnut (Trapa natans) and spiked watermilfoil (Myriophyllum spicatum) were introduced into Chesapeake Bay during the 1900s and competed with native food plants (Gwathney 1945, Rawls 1975, Bayley et al. 1978). Some areas of the bay became completely covered by exotics, which restricted growth of wildcelery (Vallisneria americana) and other submerged native plants. Native waterfowl plant foods declined in abundance during the exotic plant infestations but recovered with the demise of the exotics. Waterfowl abundance on the Susquehanna Flats, in the upper bay, seemed to be inversely related to the abundance of exotic plants (Bayley et al. 1978). Habitat changes in Chesapeake Bay were reflected in a precipitous decline in vegetation as a food of canvasbacks, which occurred concurrently with an increase of mollusks as a food item (Munro and Perry 1981, Perry et al. 1981). The dramatic change in canvasback food habits

Sediment ingestion rates in waterfowl (Anatidae) and their use in environmental risk assessment

ABSTRACT When waterfowl (Anatidae) ingest sediment as they feed, they are exposed to the environmental contaminants in those sediments. The rate of ingestion may be key to assessing environmental risk. Rates of sediment ingestion were estimated as from <2% to 22% in 16 species of waterfowl collected in the northeastern United States. The piscivorous red-breasted merganser (Mergus serrator) ingested sediment at the lowest rate and the benthos-feeding canvasback (Aythya valisineria) at the highest rate. Sediment ingestion rates were related to diet and to the sediments where waterfowl fed. Waterfowl ingested the least sediment from hard-bottomed habitats with fast-moving water and ingested the most sediment from soft-bottomed areas with slow-moving water. Understanding the greater hazards from contaminants associated with low-flow habitats may help in prioritizing sites to be remediated. The tundra swan (Cygnus columbianus), which ingests sediment at an estimated 8.4% of its diet, dry weight, is suggested as a potential generic model for use in environmental risk assessments designed to protect waterfowl.

Asiatic clam (Corbicula manilensis) and other foods used by waterfowl in the James River, Virginia

Corbicula manilensis was found in the gizzards of 24 ducks of 5 species taken from the James River, Virginia, between 1973 and 1976. Percent average volume in these species ranged from trace to 6%. This is the first known occurrence of this exotic clam in the food of duck in Chesapeake Bay. A total of 135 other food items was identified from the 116 gizzards of 9 species that were examined. Food that predominated includedCyperus spp.,Leersia oryzoides, Polygonum spp., andZea mays. The great diversity of food consumed in this fresh tidal section of the James River indicates the high value of these wetlands to waterfowl. *** DIRECT SUPPORT *** A01BY015 00008

Wetlands Mitigation: Partnership Between an Electric Power Company and a Federal Wildlife Refuge

Nine hectares (23 acres) of a degraded section of Patuxent Research Refuge in Laurel, Maryland, USA, were converted to wetland habitat by the Baltimore Gas and Electric Company in 1994. The wetlands were created as mitigation for 5.7 ha (14 acres) of wetlands that were impacted as part of the construction of an 8.5-km (5.3-mile) 500-kV overhead transmission line on the refuge. The area consists of a created forested wetland of 5.5 ha (13.5 acres), a seasonally inundated green-tree reservoir of 7.6 ha (6.5 acres), and an impounded pond wetland of 1.2 ha (3 acres). Construction included the planting of 6131 trees, 4276 shrubs, and 15,102 emergent plants. Part of the site has been studied intensively since completion and survival of trees and shrubs after two years was 88%. Measurements of these transplants have shown growth greater than on other created sites in Maryland. Grasses and other herbaceous vegetation were dominant plants in the meter-square plots in the first two years of sampling of the created forested wetland. Wildlife surveys for birds, mammals, amphibians, and reptiles have revealed diverse communities. Although these communities represent species consistent with open habitat, more typical forest species should colonize the area as it undergoes succession into a more mature forested wetland. The creation, management, and research of this mitigation site represents an excellent example of a partnership between a private electric power company and a federal wildlife refuge. This partnership has increased local biodiversity and improved regional water quality of the Patuxent River and the Chesapeake Bay.

Predation on Dovekies by Goosefish Over Deep Water in the Northwest Atlantic Ocean

Abstract Fourteen Alle alle (Dovekie) were recovered from the stomachs of 14 Lophius americanus (Goosefish) caught during winter and spring 2007–2010. All fish were caught in gill nets set at depths of 85–151 m (276–491 ft) 104–150 km (65–94 mi) south of Chatham, MA. Dovekies showed few signs of digestion by the fish, indicating recent capture. Post mortem revealed no cause of mortality. Capture of birds by fish so far from shore and in deep water leads to speculation that the birds were preyed on by Goosefish at or near the surface. Evidence from electronic tagging of Goosefish suggests that Goosefish vertical migrations could bring them into contact with Dovekies feeding offshore. If Goosefish are concentrated during onshore-offshore migrations and Dovekies are concentrated for feeding on prey patches, predation by Goosefish on Dovekies could be episodically important.

Do seaducks minimise the flightless period? Inter- and intra-specific comparisons of remigial moult.

Remigial moult is one of the crucial events in the annual life cycle of waterfowl as it is energetically costly, lasts several weeks, and is a period of high vulnerability due to flightlessness. In waterfowl, remigial moult can be considered as an energy-predation trade-off, meaning that heavier individuals would minimise the flightless period by increasing feather growth rate and energy expenditure. Alternatively, they could reduce body mass at the end of this period, thereby reducing wing-loading to increase flight capability. We studied timing of remigial moult, primary growth rates, flightlessness duration, and the pattern of body mass variation in 5 species of captive seaducks (Melanitta fusca, M. perspicillata, Clangula hyemalis, Histrionicus histrionicus, and Somateria mollissima) ranging in size from 0.5 to 2.0 kg. Their feather growth rates weakly increased with body mass (M0.059) and no correlation was found at the intra-specific level. Consequently, heavier seaduck species and especially heavier individuals had a longer flightless period. Although birds had access to food ad libidum, body mass first increased then decreased, the latter coinciding with maximum feather growth rate. Level of body mass when birds regained flight ability was similar to level observed at the beginning of remigial moult, suggesting they were not using a strategic reduction of body mass to reduce the flightlessness duration. We suggest that the moulting strategy of seaducks may be the result of a compromise between using an intense moult strategy (simultaneous moult) and a low feather growth rate without prejudice to feather quality. Despite the controlled captive status of the studied seaducks, all five species as well as both sexes within each species showed timing of moult reflecting that of wild birds, suggesting there is a genetic component acting to shape moult timing within wild birds.

Composition, shell strength, and metabolizable energy of Mulinia lateralis and Ischadium recurvum as food for wintering surf scoters (Melanitta perspicillata)

Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6–12 mm for M. lateralis and 18–24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum’s higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.